Two lists in, four answers out: lines in both, lines only in A, lines only in B, and the full union. Editable side-by-side, live update.
Two subscribers exports. Two error fingerprint dumps. A list of expected files and a list of what shipped. The question is always the same: what overlaps, what's missing, what's extra?
Compare takes two lists and returns four answers at once — intersect, A-only, B-only, union — via a single Set operation in your browser.
Drop one item per line into the left box.
Drop one item per line into the middle box.
Click IN BOTH / A ONLY / B ONLY / UNION on the right to see the four views. All update live. Hit Copy to grab the current view.
Within each view, items appear in their original input order (A-then-B for union). Lines are deduped within each list before comparison.
Case-sensitive by default — "Apple" and "apple" are different. Toggle CASE-INSENSITIVE to merge them.
Anything between \n boundaries, after optional trim. Blank lines are dropped from the input before comparison.
Not in this tool — do it pairwise. Compare A vs B, then take the result and compare against C.
Strict exact-match only — two lines are "equal" if every character matches (optionally case-insensitive). It does not do fuzzy matching, Levenshtein distance, or semantic similarity. If foo bar appears in A and foo bar (two spaces) in B, they're considered different. For fuzzy diff use a real diff tool like diff -y, Beyond Compare, or one of the JS libraries listed in our how-to-compare-two-lists blog post.
Compare has the highest memory pressure of the eight — it builds an in-memory Set per list, typically using 3–5× the original size. Comfortable up to ~100k lines per list; ~500k lines per list works on desktops with adequate memory. The output preview for each tab (Both / A-only / B-only / Union) truncates independently at 5,000 lines, but Copy always operates on the full visible view.
Yes — those three set operations map to the four tabs this tool gives you. IN BOTH is the intersection (lines common to both lists). A ONLY is the difference A − B; B ONLY is B − A (lines unique to each side). UNION is the deduped combination of both. One paste, four answers — no need to run separate operations.